special characters in url rewrite

[Majora]

Hello,
I would like to have a URL like this: http://www.rechnungswesenforum.de/th...er-das-vorjahr

URL's are lowercase and special characters are rewritten in the case ? becomes ae.

I've tried to set this:

public static function cleanURL ($ fragment)
       {
$ Translite_simbols = array (
        '?' => 'U',
        '?' => 'u',
        '?' => 'A',
        '?' => 'a',
        '?' => 'ss',
        '?' => 'o',
        '?' => 'O',
        '?' => 'c',
        '?' => 'C',
        '?' => 'g',
        '?' => 'g',
        '?' => 'u',
        '?' => 'u',
        '?' => 's',
        '?' => 'S',
        '?' => 'i',
        '?' => 'I',
        '?' => 'r',
        '?' => 'c',
        '?' => 'E',
        'Ue' => 'u',
        'Oe' => 'o'

);

in the public static function clean_entities ($ fragment) function

Unfortunately, this with vBulletin 4.2.1 Patch Level 1 does not work.

What's wrong?

Best regards
Matthias

[Majora]

Anyone?